net/macb: merge at91_ether driver into macb driver

macb and at91_ether drivers can be compiled as modules, but the at91_ether
driver use some functions and variables defined in the macb one, thus
creating a dependency on the macb driver.

Since these drivers are sharing the same logic we can easily merge
at91_ether into macb.

In order to factorize common probing logic we've added an ->init() function
to struct macb_config (the structure associated with the compatible
string), and moved macb specific init code from macb_probe to macb_init.

Signed-off-by: Cyrille Pitchen <cyrille.pitchen@atmel.com>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Tested-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/cadence/Kconfig

@@ -20,14 +20,6 @@ config NET_CADENCE
 
 if NET_CADENCE
 
-config ARM_AT91_ETHER
-	tristate "AT91RM9200 Ethernet support"
-	depends on HAS_DMA && (ARCH_AT91 || COMPILE_TEST)
-	select MACB
-	---help---
-	  If you wish to compile a kernel for the AT91RM9200 and enable
-	  ethernet support, then you should always answer Y to this.
-
 config MACB
 	tristate "Cadence MACB/GEM support"
 	depends on HAS_DMA

drivers/net/ethernet/cadence/Makefile

@@ -2,5 +2,4 @@
 # Makefile for the Atmel network device drivers.
 #
 
-obj-$(CONFIG_ARM_AT91_ETHER) += at91_ether.o
 obj-$(CONFIG_MACB) += macb.o